Cartons having various types of opening features ar well known in the art.
Exemplary of carton structures having easy opening features provided by lines of weakening in one or more layers of the carton material are the following: U.S. Pat. No. 1,992,195 issued to Daller on Feb. 26, 1935; U.S. Pat. No. 2,003,925 issued to Daller on June 4, 1935; U.S. Pat. No. 3,302,857 issued to Martin on Feb. 7, 1967; U.S. Pat. No. 3,326,364 issued to Waldrop et al. on June 20, 1967; U.S. Pat. No. 3,368,739 issued to Roccaforte et al. on Feb. 13, 1968; U.S. Pat. No. 3,438,566 issued to Mahon on Aug. 15, 1969; U.S. Pat. No. 3,885,732 issued to Foster on May 27, 1975 and U.S. Pat. No. 3,893,614 issued to Meyers on July 8, 1975.
U.S. Pat. No. 2,124,868 issued to Davidson on July 26, 1938 discloses still another prior art carton which allegedly opens easily yet which can be sealed so tightly as to prevent the sifting out of fine or powdered material. Davidson discloses a carton having front, rear and side walls, the side walls having inturned flaps and a top secured to the rear wall and overlying the flaps. The top has a glue strip at each side fixedly secured to the inturned flaps. According to Davidson, the glue strip is limited by a weakened line extending across the top on its underside only, whereby upon opening of the top the material of the glue strips will split and only their underparts will adhere to the inner flaps while the outer surface of the top remains continuous and unbroken.
It is also known in the prior art to provide carton structures having overlapping flaps which are hingedly connected to the front and back walls of the carton, said flaps being securely bonded to one another to provide a sealed, compression resistant end of the carton. To facilitate easy opening by the consumer, it has also been prior art practice to provide removable tear strips extending across the exterior overlapping flap in a direction generally parallel to the front and back walls of the carton. Although these removable tear strips work well from the standpoint of openability, they require precise registration of the adhesive utilized to bond the flaps to one another to prevent bonding of the tear strip. In addition, cartons employing such removable tear strips are oftentimes damaged prior to reaching the consumer due to the compressive loads applied to the front and back surfaces of the cartons when they are shipped and handled. Typically, this results in a prematurely opened carton which, of course, is unacceptable to the consumer.
Accordingly, it is an object of the present invention to provide an improved carton structure having a securely sealed, yet easily openable end.
It is a further object of the present invention to provide such a carton structure wherein the presence of the easy opening end does not significantly detract from the compression resistance of the carton when compressive loads are applied to opposing side wall surfaces of the carton.
It is a further object of the present invention to provide such a carton structure without utilizing any more material than would be required to provide a comparable non-easy opening carton end.
It is still another object of the present invention to provide such a carton structure which is no more difficult to erect, fill, close and seal than a comparable carton which has not been provided with an easy opening end of the present invention.